Furnace discharging device



o. D. COLLIS ETAL FuRNAcE DISCHARGING DEVICE original Filed July31,'1959 Sept. 29, 1942.

Vproduced Patented Sept. 29, 1942 2,297,289 FURNACE DISCHARGING DEVICEOliver D. Collis, Eldred C. Brace, and Emery 0.

Thompson, Clinton, Iowa, assignors to The Collis Company, Clinton,

Iowa

287,476, now December 16,

Iowa, a corporation of original application July 31, 1939, serial No.Patent No.

1941. Divided and this applica- 2,266,005, dated tion June 9,1941,Serial No. 397,280

2 Claims.

This case is a division of our application liled July 31, 1939, underSerial No. 287,476, now Patent No. 2,266,005. f

The apparatus of our invention which is adaptable for the heat treatmentof various loose materials, such for example as the roasting of rawores, is essentially a circular rotary hearth furnace in which thehearth rotates in an annular tunnel constructed of insulating material.While the advantages and objects of Vthe present furnace are many, thefeatures with which this application are particularly concerned relatelargely to the means by which the treated material may be removed fromthe furnace hearth.

A mechanism containing a suggestive embodiment of our invention is`illustrated in the accompanying drawing in the manner following:

Figure 1 is a fragmentary top plan view of the annular roof broken awayto'exhibit therebelow a rotary hearth with which is associated thepresent unloading mechanism;

Fig. 2 is a transverse section, on an enlarged scale, through the hearthand roof therefor, taken on line 2--2 of Fig. 1; and

Fig. 3 is a detailin perspective of the delivery end of the unloadingscrew shown in Fig. 2.

While reference throughout the specification is made to'an ore roaster,as a specific application of our invention,'it should be understood thatit may be applied to the heat treatment of any loose materials undercontrolled conditions, or simply to the heating, or even the drying(with or without heat) of such materials, as a continuous processwherein the material, while disposed upon a hearth, is subjected torepeated stirring, turning over, and exposure of fresh portions of itsmass, during the treating period, and (optionally) previous andsubsequent thereto.

Referring particularly to Figs. 1 and 2, the annular hearth comprises aring-shaped floor I bordered adjacent its inner and outer rims by lowwalls II and I2, respectively, all desirably from suitable refractorymaterials, and carried upon a metallic base plate I3 supported uponledges which are extended laterally. from aprons I4 and I5 adjacent theinner and outer walls, respectively. The hearth base plate is supportedupon and reinforced by cross beams I6 which are rested upon inner andouter circular beams I'I and I8, respectively. Circular flanged tracksI9 and 20 are fltted to the underside of the inner and outer circularbeams I'I and I8, respectively, each track being ladapted to ride u-ponthe upper face of a plurality of rollers 2 The depending aprons I4 andI5 are positioned within circular troughs 30 and 3|, respectively,containing a suitable uid material (water, sand, etc.) to a level 32which is above the lower edge of the apron, whereby to provide a seal`therewith. Each trough is supported upon a plurality of circularlyarranged piers, the inner ones being designated as 33 and the outer onesas 34, the space between these piers and below the hearth being open orclosed according as may be desired. Any suitable drive (not shown) maybe provided, by which the hearth is slowly revolved upon the severalwheels whereon the rails are adapted to travel.

Extended vertically from suitable foundations to the outside of thelpiers 33 and 34, are supporting beams 50, spaced at suitable intervalsand interconnected with each other and certain radially extendingoverhead beams 5I. The vertical beams support an annular roof whichsurmounts the hearth in spaced relation thereto. As shown, the troughs30 and 3l are each formed withran outwardly extended bracket 52supporting a ledge 53 from which rises a retaining plate 54 connected atintervals with the vertical supports 50 so as to be sustained thereby.-Bllilt upon each ledge and extending upwardly -along the inner face ofAeach retaining plate is a wall 55 supporting at its upper end theopposite edges of an arched annular roof 56, the walls 55 and the roofsupported thereon being desirably made, in whole'or in part, of asuitable refractory material. Also we provide through the inner andouter Walls 55 a plurality of draft openings 58, positioned, if desired,so that their lower edges are about opposite the upper edge of the innerlow wall II of the hearth. Each such opening may be closed, in whole orin part, by a suitable door (not shown). Through the outer wall 55 is ano-pening with a surrounding lining 59 of refractory material, a burner60 being tted into such opening where it is surrounded by the refractorymaterial through which is a central passageway 6I forming a dischargeorifice for flames which are projected from the burner into the annularspace between the hearth and roof. The burner is connected with aconduit 62 leading to a source of fuel supply, preferably oil or gas. Itwill be understood that a number of such burners are located adjacent anouter wall of the annular hearth, the positioning and spacing of suchburners being preferably'according to some such plan as will hereinafterbe explained.

Extending through the roof is a chute leading downwardly from anoverhead bin or hopper 86 wherein is maintained a supply of loosematerial to be treated. As by means of suitable valve mechanism (notshown) the gravity iiow of the material through the chute may becontrolled so that it will be deposited upon the hearth continuously ata rate which may be handled to best advantage. As shown, the lower endof the chute is connected to a neck 81 extending upwardly from adistributing hood 88 which extends transversely across the hearth, therebeing baffles or other walls arranged within the hood to deflect andguide a portion of the material to points adjacent the opposite rims ofthe hearth. The Ibottom side of the hood which is open may be positionedclose to the iloor of the hearth. The hood is adjustably supported as-by a pair of bolts 9| each equipped with a turn buckle 92 by which tovary the height at which the hood is supported-a desirable objective inview of the diversities of the materials and conditions to be dealtwith. Adjacent the hood and extending upwardly from a point close to thehearth is a conduit |00 which passes out through the housing to ascrubber, or directly into a stack, for discharge of gasses or productsof combustion into the atmosphere.

For a rabble mechanism we may employ a plurality of spiral blades |55each extending continuously along a shaft |56 which is disposedtransversely over the hearth, the blades at their lowermost points lyingclose to the hearth iioor so as to engage with the layer of loosematerial that rests thereon. Opposite ends of each shaft are journaledfor rotation in suitable bearings, the shaft being extended beyond theinner bearing to carry a sprocket wheel |58 over which are trainedchains connecting with a power transmission (not shown). By suitableconnections, a number of spiral blades, each extended transverselyacross the hearth, may be driven in unison so that the material which ismoved along with the hearth is constantly turned over and stirred. Thepitch of the blades on alternate rabbles may be reversed so thatstirring of the ore is equalized in the direction of its opposite rims.

Referring now to Figs. 2 and 3, we have shown an unloader comprising ashaft |10 mounted to rotate transversely over the hearth atsubstantially the point where the treated material is to be removedtherefrom, and equipped with a sprocket wheel |1| (or two, if desired)by which power may be conveniently transmitted thereto. Carried uponthis shaft is a hub |12 mounting a large diameter screw |13 having thelower portion of each convolution in close proximity to the hearth sothat, when operated, the loose material will be engaged thereby to beshifted transversely towards the outer hearth rim. At the outer end ofthe screw we have affixed a radial ange |14 extending outwardly close tothe proximate rim of the hearth, adapted to act upon the loose materialwhich may have collected at that point, first raising and then droppingthe material upon a ledge |15 from which it descends along an inclinedchute |16 to a dis-charge station (not shown).

The material to be treated is conveyed to the hopper'or bin from whichit is released for a controlled discharge into the distributing hoodimmediately over the hearth. As the hearth rotates it carries thematerial with it concentrically.

It advances along with the hearth through nearly 360 of movement,returning to approximately its point of introduction. The material mayremain on the hearth for one or more revolutions, the desirability ofthis depending upon various factors, such as temperature, nature ofmaterial, speed of rotation, etc. stirring of the ore is accomplished bythe several spiral rabbles which are spaced apart, as desired, eachrevolving about a horizontal axis which remains stationary. Thecombination of the rotating hearth traveling against the rotatingrabbles produces a slow, persistent turning over of the material on thehearth bed.

In conclusion we would have it noted that in the` present mechanismthere is a positive movement of all the material, as it advances alongupon the hearth bed, the material being iinally returned to its originalpoint of entry; and there is a thorough stirring of the material due tothe unique movement occasioned by the rotatable advance of the hearthwhile continuous rotary movement of the several spiral rabbles proceeds.Such a hearth, which advances through a rotary path, permits an absolutecontrol of such factors as time, temperature, zoning and movement of thematerial particles.

l. A treating mechanism in which is comprised an annular hearth mountedfor rotation about a iixed axis, a stationary annular roof supportedabove the hearth, means for delivering loose material upon the hearthland means for removing the loose material from the hearth at a xed pointin the rotation of the latter comprising a screw mounted for rotationabout .a horizontal axis extending radially of the hearth at anelevation thereabove such that the lower portion of each convolution ofthe screw engages within the bed of loose material upon the hearth, adischarge chute adjacent one end of the screw, and means carried by thescrew convolution at the outer end thereof proximate to the chute forlifting material from the hearth to a point of gravity discharge throughthe chute. an elevated unobstructed lateral passageway to the chutebeing arranged to receive material from the material elevating means ofthe conveyor when such means is in an elevated position.

2. A treating mechanism in which is comprised a hearth movable through afixed path, and means for removing loose material from the hearth at axed point in its movement path comprising a screw mounted for rotationabout a substantially horizontal axis extending over the hearth at anelevation thereabove such that the lower portion of each convolution ofthe screw engages within the bed of loose material to advance theengaged material along the hearth in a direction axially of the screw, adischarge chute adjacent the delivery end of the screw, and meansproximate to the Vchute connected for rotation with the screw adapted toengage and lift the advanced material from the hearth to a point ofgravity discharge through the chute, an elevated unobstructed lateralpassageway to the chute being arranged to receive material from thematerial elevating means of the conveyor when such means isin anelevated position.

OLIVER D. COLLIS. ELDRED C. BRACE. EMERY O. THOMPSON.

